The class of polymers of carbon monoxide and olefin(s) has been known for a number of years. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical catalysts, i.e., peroxy compounds. U.K. Pat. No. 1,081,304 produced similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium salts as catalyst. Nozaki extended this process through the use of arylphosphine complexes of palladium, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon, e.g., polymers of carbon monoxide and ethylene or ethylene and propylene, has become of greater interest because of the greater availability of the polymers. These polymeric materials, also known as polyketones, have been shown to be of the formula --CO--(A)-- where A is the moiety obtained by polymerization of the hydrocarbon through the ethylenic unsaturation. For example, when the unsaturated hydrocarbon is ethylene the polymer is represented by the formula --CO--CH.sub.2 --CH.sub.2 --. The general process for the production of such polymers is shown by published European Patent Application Nos. 0,121,965 and 0,181,014. The process generally involves the use of a catalyst composition formed from a compound of a Group VIII metal selected from palladium, cobalt or nickel, the anion of a non-hydrohalogenic acid having a pKa less than 2 and a bidentate ligand of phosphorus, arsenic or antimony.
The class of polyketones is characterized by relatively high melting points, generally over 175.degree. C. and frequently over 210.degree. C. As the polymers are useful as premium thermoplastics, they are frequently processed at elevated temperatures at or near the melting point. During such processing, the polymer is often heated in air to such elevated temperature and maintained at the elevated temperature for a period of time which will vary with the nature of the processing. Although the polyketone polymers are relatively stable at such temperatures, they will undergo heat or oxidative deterioration depending in part on the nature and melting point of the particular polymer.
Methods are available to stabilize the carbon monoxide/ethylene copolymers against heat or thermal degradation as determined by cross-linking of the polymer. Russell et al discloses the use of certain benzophenones, U.S. Pat. No. 3,929,727, or certain benzotriazoles, U.S. Pat. No. 4,024,104, to stabilize these copolymers against thermal degradation. Hudgin stabilizes such polymers against thermal degradation by using organic epoxy compounds (U.S. Pat. No. 3,948,832), phosphoric acid salts (U.S. Pat. No. 3,948,850) or organic polythiol compounds (U.S. Pat. No. 3,968,082). Lantor, U.S. Pat. No. 4,139,522 uses manganous salts of phosphorus oxyacids for the same purpose. It would be of advantage to provide polyketone polymers of improved stability against oxidative deterioration.